CVE-2026-14257: DoS (CVSS 7.5)

Description

brace-expansion through 5.0.7 is vulnerable to denial of service via memory exhaustion. The expand() function limits the number of results with a max option (default 100,000) but does not bound the length of each result string. By chaining multiple brace groups, an attacker keeps the result count under the limit while making each result progressively longer, so total memory scales with both count and string length until the process hits a fatal, uncatchable out-of-memory error. About 7.5 KB of input ('{a,b}'.repeat(1500)) crashes a default Node.js process. Any application that passes attacker-influenced strings to brace-expansion.expand() - directly or transitively via minimatch / glob brace patterns - can be crashed by a small request. Fixed in 5.0.8 by adding a maxLength option (default 4,000,000) that bounds accumulated output and intermediate arrays.

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CVSS v3.1 Score

7.5

HIGH

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS — Exploit Prediction

0.0034

Probability of exploitation

0.26%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-400 Uncontrolled Resource Consumption

CWE-770 CWE-770

References

Other References

https://github.com/juliangruber/brace-expansion https://github.com/juliangruber/brace-expansion/commit/a1bd33999ea75262c4749fff3bbb0d1372bd07b5 https://www.npmjs.com/package/brace-expansion

Frequently Asked Questions

What is CVE-2026-14257? +

brace-expansion through 5.0.7 is vulnerable to denial of service via memory exhaustion. The expand() function limits the number of results with a max option (default 100,000) but does not bound the length of each result string. By chaining multiple brace groups, an attacker keeps the result count under the limit while making each result progressively longer, so total memory scales with both count and string length until the process hits a fatal, uncatchable out-of-memory error. About 7.5 KB of input ('{a,b}'.repeat(1500)) crashes a default Node.js process. Any application that passes attacker-influenced strings to brace-expansion.expand() - directly or transitively via minimatch / glob brace patterns - can be crashed by a small request. Fixed in 5.0.8 by adding a maxLength option (default 4,000,000) that bounds accumulated output and intermediate arrays. It has a CVSS v3.1 base score of 7.5 (HIGH).

How severe is CVE-2026-14257? +

CVE-2026-14257 has a CVSS v3.1 score of 7.5 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching. The EPSS score is 0.0034, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-14257? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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